Wolff-Parkinson-White syndrome classification scheme

Wolff-Parkinson-White syndrome Microchapters
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Differentiating Wolff-Parkinson-White syndrome from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
Approach
History and Symptoms
Electrocardiogram
EKG Examples
Other Diagnostic Studies
Treatment
Risk Stratification
Cardioversion
Medical Therapy
Catheter Ablation
Prophylaxis
Consensus Statement
Case Studies
Case #1
Wolff-Parkinson-White syndrome classification scheme On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Wolff-Parkinson-White syndrome classification scheme
CDC onWolff-Parkinson-White syndrome classification scheme
Wolff-Parkinson-White syndrome classification scheme in the news
Blogs on Wolff-Parkinson-White syndrome classification scheme
Directions to Hospitals Treating Deep vein thrombosis
Risk calculators and risk factors for Wolff-Parkinson-White syndrome classification scheme

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Classification

Classification Based on the ECG Findings

This classification is based on the side where the accessory pathway is established. The type A preexcitation presents the accessory pathway in the left side of the heart (comunicates the left atrium with the left ventricle). The type B preexcitation presents the accessory pathway in the right side of the heart (comunicates the right atrium with the right ventricle). Each type of preexcitation presents its own electrocardiographyc characteristics.

1. Type A:
   • Prominent R wave in lead V1 and V2.
   • It has been found at EP studies that these patients have early activation of the left ventricle.
   • Generally V1 shows either a notched R wave or RS or Rsr' deflection.
   • Mimics a posterior MI, RVH.
2. Type B:
   • Prominent S wave deflection in the right precordial leads, and upright R waves in the lateral precordial leads.
   • EP studies have showed that this form of WPW syndromes is due to early activation of the lateral aspect of the right ventricle
   • This form is more common.
   • May resemble an abnormal Q wave in the right precordial leads and be mistaken for an anterior MI.
   • In both type A and B there may be abnormal q waves in leads 2, 3 and aVF.

Variants of WPW

Lown-Ganong-Levine Syndrome (LGL)

• There is a short PR interval, but no delta wave
• LGL is due to intranodal bypass tracts (i.e. there is conduction down the James fibers)
• Normal QRS duration
• PR less than 0.12 seconds
• Normal P wave

Mahaim Type Preexcitation

• This form of pre-excitation is due to nodoventricular, nodofascicular or fasciculoventricular connections
• The impulse may travel through the AV node normally and this may then be followed by premature conduction to the basal ventricular myocardium
• There is a delta wave with a normal PR interval
• Rarer than WPW or LGL
• In older patients there can be a prolonged conduction down the accessory pathway resulting in a normal PR interval in the presence of WPW which is tough to distinguish from Mahaim fibers